Financial site WalletHub ranked states on the estimated costs of smoking over a lifetime. To find these numbers, the site looked at such factors as cumulative cost of a cigarette pack per day over several decades, health-care expenditures, income losses and other costs.

Financial site WalletHub ranked states on the estimated costs of smoking over a lifetime. To find these numbers, the site looked at such factors as cumulative cost of a cigarette pack per day over several

Close to a billion people smoke cigarettes daily, meaning there are more smokers today than at any other time in history.

This startling figure is easily accounted for: As the global population rises, so too does the number of smokers. In the past 25 years, the percentage of people who smoke has dropped by 25 percent.

Only five percent of women smoke daily, while 25 percent of their male counterparts light up at least once a day, says a new paper funded by the Bill and Melinda Gates Foundation and Bloomberg Philanthropies. The paper, which was published in the Lancet, found that the United States boasts more female smokers than any other country.

Related video: 1 in 10 deaths are smoking-related

A new study found that smoking causes one in 10 deaths worldwide. Despite tobacco control policies, population growth increased the number of smokers. The study found that one in four men is a daily smoker, while one in every 20 women is a smoker. "Smoking remains the second largest risk factor for early death and disability, and so to further reduce its impact we must intensify tobacco control to further reduce smoking prevalence and attributable burden," Dr. Emmanuela Gakidou, senior author

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This likely correlates to the country's income; female smokers are most common in wealthy countries, while low-income countries have the fewest smokers across the board.

Smoking accounted for 11.5 percent of worldwide deaths in 2015, over 50 percent of which occurred in just four countries (China, India, the US, and Russia). This figure makes smoking the second leading risk factor early death worldwide (high blood pressure is number one).

As for prevention, the study cites the most effective measures as taxation, bans on public smoking, restrictions on marketing, community-wide smoking cessation interventions, and warning labels on marketing.